Switch linuxbridge-scenario job to be voting

As failure rate of tempest-plugin-scenario-linuxbridge
job in check queue is low we decided to make this job
voting in check queue.
If it will work fine in check queue we will set it
to be running also in gate queue.

Change-Id: I096802f0a6b48da8eedfe4e992d7d324c3018c40

.zuul.yaml

@@ -41,7 +41,6 @@
       - ^neutron/tests/unit/.*$
       - ^tools/.*$
       - ^tox.ini$
-    voting: false
 
 - job:
     name: neutron-tempest-plugin-dvr-multinode-scenario